我国南方花生发生一种由蕃茄斑萎病毒引起的新病害

我们于1984和1985年6月上、中旬,在广州市郊、县,湛江市郊以及广西南宁市郊、县,北海市郊和合蒲县等花生产区,调查花生病毒病时,除了发现花生轻斑驳病毒病外,还发现一种新的病毒病害。其症状特征是:病株顶端叶片上出现很多褪绿黄斑或环斑,有的环斑变     

Wound-induced changes in the acceptability of tomato to larvae of Spodoptera littoralis: a laboratory bioassay

Abstract. 1. Leaves of tomato (cv. Moneymaker) were artificially damaged and offered to Spodoptera larvae at a range of intervals following damage. Grazing levels on these leaves were compared with those on undamaged leaves on the same or different plants.
2. In separate experiments, three leaves in a middle position on the main stem were clipped and after 48 h grazing levels on undamaged leaves above and below those damaged were compared with similar leaves from control plants.
3. Within 8 h, grazing levels on damaged leaves were significantly lower than those on control leaves, and within 24 h, leaves adjacent to damaged ones were similarly affected. These effects persisted for at least 7 days and leaves above and below those damaged were affected. There was up to nine-fold reduction in area consumed.
4. The possible ecological consequences of reduced palatability at these levels are discussed.     

Benomyl: A broad spectrum fungicide for use in plant cell and protoplast culture

The systemic fungicide methyl-1-(butylcarbamoyl)-2-benzimidazole carbamate (benomyl), is a broad spectrum fungicide. Benomyl at concentrations up to 50 mg/l does not inhibit the growth of suspension cultures ofNicotiana tabacum, Datura innoxia, Daucus carota, Glycine canescens, andSolanum tuberosum nor growth ofN. tabacum orN. plumbaginifolia protoplasts if benomyl is dissolved by autoclaving or boiling. Addition of benomyl dissolved in dimethyl sulfoxide results in a visible toxicity. Benomyl, at 6.25–50 mg/l preventsPenicillium spp. growth in both protoplast and cell cultures and can be used to remove fungal contaminates after one to three transfers without visibly retarding plant cell growth. Due to the broad spectrum of fungicidal activity, and nontoxicity at high concentrations when dissolved by boiling or autoclaving, benomyl can be used effectively to control or prevent fungal contamination in plant cell and protoplast cultures.     

Kinetics of ammonium and nitrate uptake among wild and cultivated tomatoes

Summary Concentration dependence of net ammonium and nitrate uptake was monitored for a cultivar of tomato, Lycopersicon esculentum, and two accessions of a neotropical wild relative, L. hirsutum. The kinetics of net NH ₄ ⁺ uptake differed among these taxa and were not dependent on the ionic composition of the nutrient solution. The kinetics of net NO ₃ ^- uptake were dependent on the composition of the nutrient solution; the presence of NH ₄ ⁺ or Cl^- enhanced net NO ₃ ^- uptake for the cultivated species and for a highland accession of the wild species. The capacity for net NO ₃ ^- uptake was greater than the capacity for net NH ₄ ⁺ uptake in all three taxa; the proportion of NO ₃ ^- to NH ₄ ⁺ absorbed was much greater for the wild taxa. Our data suggest that NO ₃ ^- may be a more important source of mineral nitrogen than NH ₄ ⁺ for these tropical taxa.     

Recombination in sesquidiploid hybrids of Lycopersicon esculentum × Solanum lycopersicoides and derivatives

Summary Sesquidiploid hybrids of L. esculentum (L) x S. lycopersicoides (S) were backcrossed to L via L. pennellii (P) as a bridging species in order to detect and measure recombination. Although use of P injected its traits into the populations, the investigated traits were proven to originate from S. The appearance of S traits in diploids in the immediate progeny of sesquidiploids but mainly of derived alien addition types proved the occurrence of recombination at rates varying from 1.6% to 16%. In subsequent BC's, these traits were inherited in dominant Mendelian fashion, except for deviations favoring recurrent parent alleles, sometimes with highly significant deviations from 11. Inheritance was investigated in BC and F₂ ex BC for 13 traits with strong phenotypic modifications of morphological, physiological, and isozymic nature. Monogenic determination was confirmed in most instances by tight linkages. For most of the traits, small progenies allowed only rough estimates of linkage intensities, but for Wa (gene for White anthers, universal in S), a test cross with four markers on chromosome 8 established its locus 2 cM distal to dl, proximally on 8L. Also noteworthy is the linkage of Dls, a gene determining sensitivity of flowering to long days, close to sp, situated subterminally on 6L. For the majority of traits, these manifestations of linkage proved that the appearance of S traits resulted from recombination, not alien chromosome substitution — a conclusion also reinforced by observations of chromosome pairing in alien addition types and diploid derivatives. Recombined S alleles have loci in various chromosome positions. Although they were discovered on the shorter chromosomes (nos. 6–12), hybridization barriers precluded tests with the longer chromosomes. Thus, no evidence was found for restriction of recombination to certain chromosomes or chromosomal regions. The prospects therefore appear favorable for deriving valuable traits from the S parent.     

Use of molecular markers in breeding for soluble solids content in tomato — a re-examination

Summbary Through earlier breeding efforts, portions of the genome of the wild species Lycopersicon chmielewskii have been introgressed into the cultivated tomato (Rick 1974). These introgressed chromosomal segments have been reported to increase soluble solids in fruit of certain tomato varieties (Rick 1974). Recently, two of the introgressed segments have been identified with RFLP markers and tested for effects on soluble solids in a single F2 population (Osborn et al. 1987). Based on results from that experiment, it was determined that one of the detected segments contains gene(s) controlling soluble solids and concluded that tomato varieties could be improved for this character by indirect selection for the linked RFLP marker (Osborn et al. 1987). In this report, we have independently tested the association between RFLP and isozyme markers and genes controlling soluble solids and other characters in the above described material. These experiments differ from the previous ones in that a set of 132 molecular markers (isozymes and DNA clones) of known chromosomal position have been used. Three introgressed chromosomal segments from L. chmielewskii have been identified using these markers. They map to the middle and the end of chromosome 7 (> 40 cM apart) and to the end of chromosome 10. The effects of these segments on soluble solids and other horticultural characters were tested in crosses with three different cultivars over a period of two years. Two of the three segments were found to increase soluble solids, however the effect of one of these was dependent on genetic background. Both segments were found to be associated with deleterious characters including increase in fruit pH, lower yield and small fruit. These results confirm the utility of molecular markers for detecting genes underlying quantitative variation but demonstrate the danger in establishing breeding programs around such linkages until the effects of the quantitative genes have been tested in a variety of genetic backgrounds and for associated effects on other characters of agronomic importance.     

苋菜的光合特性

宽菜Amaranthus cruentus cv.生长在调控的温室条件。在光强0至800μmol.m~(-2)S~(-1),光合速率(PN,μmol.CO_2m~(-2)、s~(-1))随光强(PFD,μmol、m~(-2)、s~(-1))增高而增大,其关系为PN=56.82 PFD×10~(-3)—2.13。光补偿点为60μmol.m~(-2)、s~(-1)。叶片在1400 μmol.m~(-2)、s~(-1)达到光合光饱和点。在叶温35℃,叶片/空气水蒸汽压陡度20 m Pa、Pa~(-1)和外界CO_2浓度340μ1、1~(-1),光饱和光合速率为51.63±4.90μ mol.CO_2、m~(-2)、S~(-1)。在光强0至600μmol.m~(-2)、s~(-1),气孔传道率随光强增高而增大。光强高于600μmol.m~(-2)、s~(-1),气孔传道率变化较小。细胞间CO_2浓度为120μ1.1~(-1)由于细胞间CO_2浓度在光合速率——CO_2关系曲线的转折点,可能表明光合作用不受气孔限制。结果表明,苋菜适于高光强环境生长,在干旱条件下具有高的光合速率。     

Molecular characterization of tomato fruit polygalacturonase

Summary Using the expression vector gt11 and immunological detection, cDNA clones of an endopolygalacturonase gene of tomato (Lycopersicon esculentum Mill.) were isolated and sequenced. The 1.6 kb cDNA sequence predicts a single open reading frame encoding a polypeptide of 457 amino acids. The PG2A isoform of tomato fruit endopolygalacturonase was purified and 80% of the amino acid sequence determined. The amino acid sequence predicted by the cDNA sequence was identical to the amino acid sequence of the PG2A isoform. The position of the codon for the N-terminal amino acid of mature PG2A in the open reading frame indicates the presence of a 71 amino acid N-terminal signal peptide which is post-translationally processed. The C-terminus of purified PG2A occurred 13 amino acids before the stop codon in the cDNA suggesting that C-terminal processing of PG2A may also occur. The nucleotide and amino acid sequence data predict a mature protein of 373 amino acids and a polypeptide molecular weight of 40279. The sequence contains four potential glycosylation sites. Northern analysis detected endopolyga-lacturonase mRNA in stage 3 (turning) and stage 6 (red) ripening fruit, but not in leaves, roots, or green fruit of normal cultivars or in mature fruit of the rin mutant.     

Regeneration of somatic hybrid plants formed between Lycopersicon esculentum and L. pennellii

Summary Somatic hybrid plants have been regenerated following polyethylene glycol mediated fusion of leaf mesophyll protoplasts from tomato and protoplasts from Lycopersicon pennellii callus. Three different cultivars of tomato were used as sources of protoplasts: Early Girl, Manapal, and UC82B. Fusions were performed between protoplasts of these tomato cultivars and protoplasts of L. pennellii, and between protoplasts of the cultivars and protoplasts of L. pennellii that had been exposed to 3 or 6 krads of gamma radiation. Somatic hybrid plants were identified on the basis of heterozygous isozyme banding patterns, and leaf and flower morphology. Somatic hybrid plants were regenerated following fusion of tomato protoplasts with either untreated or irradiated L. pennellii protoplasts. All were heterozygous for isozyme loci on five different chromosomes. Regenerated somatic hybrids showed inheritance of either or both parental chloroplast genomes, but predominantly the L. pennellii mitochondrial genome. The regenerated somatic hybrid plants exhibited reduced fertility, less than 20% viable pollen. A total of 34 somatic hybrid calli were identified. Of these, 21 regenerated shoots, and 7 produced seed following manual pollinations.     

Metal speciation in xylem and phloem exudates

Summary Two computer programs based on simultaneous chemical equilibria were compared for calculation of chemical species in xylem exudates. The first program, CHELATE, was developed to calculate the chemical species in xylem exudates while GEOCHEM was developed to calculate the speciation of natural aquatic systems. The output of the two programs should be similar since they are based on similar calculations. Data input to the programs consisted of concentration data for Ca, Cu, Fe, Mg, Mn, Zn, NH₄, PO₄, pH and 28 organic ligands reported for xylem exudates from soybean (Glycine max (L.) Merr.) and tomato (Lycopersicon esculentum Mill.) plants grown in nutrient solution¹⁷. The organic ligands included amino acids and low molecular weight organic acids (e.g., citric and malic). With the exception of Fe, there were large differences between CHELATE and GEOCHEM in the calculated speciation of nearly all metals in the xylem exudates. In general, there was better agreement between the programs for the speciation of alkaline earth metals than for transition metals. Discrepancies between the two programs were attributed to differences in 1) species considered and 2) stability constants. GEOCHEM considered a greater number of possible complexes. In addition, stability constants for some complexes differed by as much as 10 fold between the two programs. When the data base for GEOCHEM and CHELATE were the same, the output from CHELATE and GEOCHEM was almost identical. Thus, computations performed by the two programs are equally valid, but it is essential that the data base used in chemical models be verified before interpreting the output. Average concentration data for Al, Au, Ca, Cu, Fe, K, La, Mg, Mn, Na, Rb, Zn, Cl, MoO₄, PO₄, SO₄, HVO₄, pH and 18 organic ligands in phloem exudates from Yucca (Yucca flaccida Haw.) were complied from available literature and analyzed by GEOCHEM. Amino acids were the predominant organic ligand analyzed. Calculations revealed that alkali metals existed almost totally as the free ionic species (≥99%) whereas alkaline earth metals were transported as complexes with organic acids (oxalic, malic, and asparagine). Aluminum and Fe were present as hydroxyl species while <1% of micronutrients were transported as the free ion. Major micronutrient species were Cu-glutamine, Mn-asparagine and Zn-alanine. Information on calculated species present in phloem exudates could be useful to guide studies for isolation of metal-ligand complexes in phloem exudates.